小开

Use GregorianCalendar. Set the date of the object, and then use getActualMaximum(Calendar.DAY_IN_MONTH).

http://docs.oracle.com/javase/7/docs/api/java/util/GregorianCalendar.html#getActualMaximum%28int%29 (but it was the same in Java 1.4)

小开

最佳答案

Java 8 and above.

By using convertedDate.getMonth().length(convertedDate.isLeapYear()) where convertedDate is an instance of LocalDate.

String date = "1/13/2012";
LocalDate convertedDate = LocalDate.parse(date, DateTimeFormatter.ofPattern("M/d/yyyy"));
convertedDate = convertedDate.withDayOfMonth(
convertedDate.getMonth().length(convertedDate.isLeapYear()));

Java 7 and below.

By using getActualMaximum method of java.util.Calendar:

String date = "1/13/2012";
SimpleDateFormat dateFormat = new SimpleDateFormat("MM/dd/yyyy");
Date convertedDate = dateFormat.parse(date);
Calendar c = Calendar.getInstance();
c.setTime(convertedDate);
c.set(Calendar.DAY_OF_MONTH, c.getActualMaximum(Calendar.DAY_OF_MONTH));

小开

This looks like your needs:

http://obscuredclarity.blogspot.de/2010/08/get-last-day-of-month-date-object-in.html

code:

import java.text.DateFormat;
import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;


//Java 1.4+ Compatible
//
// The following example code demonstrates how to get
// a Date object representing the last day of the month
// relative to a given Date object.


public class GetLastDayOfMonth {


public static void main(String[] args) {


Date today = new Date();


Calendar calendar = Calendar.getInstance();
calendar.setTime(today);


calendar.add(Calendar.MONTH, 1);
calendar.set(Calendar.DAY_OF_MONTH, 1);
calendar.add(Calendar.DATE, -1);


Date lastDayOfMonth = calendar.getTime();


DateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
System.out.println("Today            : " + sdf.format(today));
System.out.println("Last Day of Month: " + sdf.format(lastDayOfMonth));
}


}

Output:

Today            : 2010-08-03
Last Day of Month: 2010-08-31

小开

The simplest way is to construt a new GregorianCalendar instance, see below:

Calendar cal = new GregorianCalendar(2013, 5, 0);
Date date = cal.getTime();
DateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
System.out.println("Date : " + sdf.format(date));

Output:

Date : 2013-05-31

Attention:

month the value used to set the MONTH calendar field in the calendar. Month value is 0-based e.g. 0 for January.

小开

I use this one-liner on my JasperServer Reports:

new SimpleDateFormat("yyyy-MM-dd").format(new SimpleDateFormat("yyyy-MM-dd").parse(new java.util.Date().format('yyyy') + "-" + (new Integer (new SimpleDateFormat("MM").format(new Date()))+1) + "-01")-1)

Doesn't look nice but works for me. Basically it's adding 1 to the current month, get the first day of that month and subtract one day.

小开

With Java 8 DateTime / LocalDateTime :

String dateString = "01/13/2012";
DateTimeFormatter dateFormat = DateTimeFormatter.ofPattern("MM/dd/yyyy", Locale.US);
LocalDate date = LocalDate.parse(dateString, dateFormat);
ValueRange range = date.range(ChronoField.DAY_OF_MONTH);
Long max = range.getMaximum();
LocalDate newDate = date.withDayOfMonth(max.intValue());
System.out.println(newDate);

OR

String dateString = "01/13/2012";
DateTimeFormatter dateFormat = DateTimeFormatter.ofPattern("MM/dd/yyyy", Locale.US);
LocalDate date = LocalDate.parse(dateString, dateFormat);
LocalDate newDate = date.withDayOfMonth(date.getMonth().length(date.isLeapYear()));
System.out.println(newDate);

Output:

2012-01-31

LocalDateTime should be used instead of LocalDate if you have time information in your date string . I.E. 2015/07/22 16:49

小开

You can use the following code to get last day of the month

public static String getLastDayOfTheMonth(String date) {
String lastDayOfTheMonth = "";


SimpleDateFormat formatter = new SimpleDateFormat("dd-MM-yyyy");
try{
java.util.Date dt= formatter.parse(date);
Calendar calendar = Calendar.getInstance();
calendar.setTime(dt);


calendar.add(Calendar.MONTH, 1);
calendar.set(Calendar.DAY_OF_MONTH, 1);
calendar.add(Calendar.DATE, -1);


java.util.Date lastDay = calendar.getTime();


lastDayOfTheMonth = formatter.format(lastDay);
} catch (ParseException e) {
e.printStackTrace();
}
return lastDayOfTheMonth;
}

小开

By using java 8 java.time.LocalDate

String date = "1/13/2012";
LocalDate lastDayOfMonth = LocalDate.parse(date, DateTimeFormatter.ofPattern("M/dd/yyyy"))
.with(TemporalAdjusters.lastDayOfMonth());

小开

Works fine for me with this

    Calendar cal = Calendar.getInstance(TimeZone.getTimeZone());
cal.set(Calendar.MONTH, month-1);
cal.set(Calendar.YEAR, year);
cal.add(Calendar.DATE, -1);
cal.set(Calendar.DAY_OF_MONTH,
cal.getActualMaximum(Calendar.DAY_OF_MONTH));
cal.set(Calendar.HOUR_OF_DAY, 0);
cal.set(Calendar.MINUTE, 0);
cal.set(Calendar.SECOND, 0);
cal.set(Calendar.MILLISECOND, 0);
return cal.getTimeInMillis();

小开

public static String getLastDayOfMonth(int year, int month) throws Exception{
DateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");


Date date = sdf.parse(year+"-"+(month<10?("0"+month):month)+"-01");


Calendar calendar = Calendar.getInstance();
calendar.setTime(date);


calendar.add(Calendar.MONTH, 1);
calendar.set(Calendar.DAY_OF_MONTH, 1);
calendar.add(Calendar.DATE, -1);


Date lastDayOfMonth = calendar.getTime();


return sdf.format(lastDayOfMonth);
}
public static void main(String[] args) throws Exception{
System.out.println("Last Day of Month: " + getLastDayOfMonth(2017, 1));
System.out.println("Last Day of Month: " + getLastDayOfMonth(2017, 2));
System.out.println("Last Day of Month: " + getLastDayOfMonth(2017, 3));
System.out.println("Last Day of Month: " + getLastDayOfMonth(2017, 4));
System.out.println("Last Day of Month: " + getLastDayOfMonth(2017, 5));
System.out.println("Last Day of Month: " + getLastDayOfMonth(2017, 6));
System.out.println("Last Day of Month: " + getLastDayOfMonth(2017, 7));
System.out.println("Last Day of Month: " + getLastDayOfMonth(2017, 8));
System.out.println("Last Day of Month: " + getLastDayOfMonth(2017, 9));
System.out.println("Last Day of Month: " + getLastDayOfMonth(2017, 10));
System.out.println("Last Day of Month: " + getLastDayOfMonth(2017, 11));
System.out.println("Last Day of Month: " + getLastDayOfMonth(2017, 12));
System.out.println("Last Day of Month: " + getLastDayOfMonth(2018, 1));
System.out.println("Last Day of Month: " + getLastDayOfMonth(2018, 2));
System.out.println("Last Day of Month: " + getLastDayOfMonth(2018, 3));


System.out.println("Last Day of Month: " + getLastDayOfMonth(2010, 2));
System.out.println("Last Day of Month: " + getLastDayOfMonth(2011, 2));
System.out.println("Last Day of Month: " + getLastDayOfMonth(2012, 2));
System.out.println("Last Day of Month: " + getLastDayOfMonth(2013, 2));
System.out.println("Last Day of Month: " + getLastDayOfMonth(2014, 2));
System.out.println("Last Day of Month: " + getLastDayOfMonth(2015, 2));
System.out.println("Last Day of Month: " + getLastDayOfMonth(2016, 2));
System.out.println("Last Day of Month: " + getLastDayOfMonth(2017, 2));
System.out.println("Last Day of Month: " + getLastDayOfMonth(2018, 2));
System.out.println("Last Day of Month: " + getLastDayOfMonth(2019, 2));
System.out.println("Last Day of Month: " + getLastDayOfMonth(2020, 2));
System.out.println("Last Day of Month: " + getLastDayOfMonth(2021, 2));
}

output:

Last Day of Month: 2017-01-31
Last Day of Month: 2017-02-28
Last Day of Month: 2017-03-31
Last Day of Month: 2017-04-30
Last Day of Month: 2017-05-31
Last Day of Month: 2017-06-30
Last Day of Month: 2017-07-31
Last Day of Month: 2017-08-31
Last Day of Month: 2017-09-30
Last Day of Month: 2017-10-31
Last Day of Month: 2017-11-30
Last Day of Month: 2017-12-31
Last Day of Month: 2018-01-31
Last Day of Month: 2018-02-28
Last Day of Month: 2018-03-31
Last Day of Month: 2010-02-28
Last Day of Month: 2011-02-28
Last Day of Month: 2012-02-29
Last Day of Month: 2013-02-28
Last Day of Month: 2014-02-28
Last Day of Month: 2015-02-28
Last Day of Month: 2016-02-29
Last Day of Month: 2017-02-28
Last Day of Month: 2018-02-28
Last Day of Month: 2019-02-28
Last Day of Month: 2020-02-29
Last Day of Month: 2021-02-28

小开

You can make use of the plusMonths and minusDays methods in Java 8:

// Parse your date into a LocalDate
LocalDate parsed = LocalDate.parse("1/13/2012", DateTimeFormatter.ofPattern("M/d/yyyy"));


// We only care about its year and month, set the date to first date of that month
LocalDate localDate = LocalDate.of(parsed.getYear(), parsed.getMonth(), 1);


// Add one month, subtract one day
System.out.println(localDate.plusMonths(1).minusDays(1)); // 2012-01-31

小开

Java 8 and above:

import java.time.LocalDate;
import java.time.Year;


static int lastDayOfMonth(int Y, int M) {
return LocalDate.of(Y, M, 1).getMonth().length(Year.of(Y).isLeap());
}

subject to Basil Bourque's comment

import java.time.YearMonth;


int lastDayOfMonth = YearMonth.of(Y, M).lengthOfMonth();

小开

tl;dr

YearMonth                            // Represent the year and month, without a date and without a time zone.
.from(                               // Extract the year and month from a `LocalDate` (a year-month-day).
LocalDate                        // Represent a date without a time-of-day and without a time zone.
.parse(                          // Get a date from an input string.
"1/13/2012" ,                // Poor choice of format for a date. Educate the source of your data about the standard ISO 8601 formats to be used when exchanging date-time values as text.
DateTimeFormatter            // Specify a formatting pattern by which to parse the input string.
.ofPattern( "M/d/uuuu" )     // Match the pattern of your input.
)                                // Returns a `LocalDate` object.
)                                    // Returns a `YearMonth` object.
.atEndOfMonth()                      // Determines the last day of the month for that particular year-month, and returns a `LocalDate` object.
.toString()                          // Generate text representing the value of that `LocalDate` object using standard ISO 8601 format.

See this code run live at IdeOne.com.

2012-01-31

`YearMonth`

The YearMonth class makes this easy. The atEndOfMonth method returns a LocalDate. Leap year in February is accounted for.

First define a formatting pattern to match your string input.

DateTimeFormatter f = DateTimeFormatter.ofPattern( "M/d/uuuu" ) ;

Use that formatter to get a LocalDate from the string input.

String s = "1/13/2012" ;
LocalDate ld = LocalDate.parse( "1/13/2012" , f ) ;

Then extract a YearMonth object.

YearMonth ym = YearMonth.from( ld ) ;

Ask that YearMonth to determine the last day of its month in that year, accounting for Leap Year in February.

LocalDate endOfMonth = ym.atEndOfMonth() ;

Generate text representing that date, in standard ISO 8601 format.

String output = endOfMonth.toString() ;

About java.time

The java.time framework is built into Java 8 and later. These classes supplant the troublesome old legacy date-time classes such as java.util.Date, Calendar, & SimpleDateFormat.

The Joda-Time project, now in maintenance mode, advises migration to the java.time classes.

To learn more, see the Oracle Tutorial. And search Stack Overflow for many examples and explanations. Specification is JSR 310.

You may exchange java.time objects directly with your database. Use a JDBC driver compliant with JDBC 4.2 or later. No need for strings, no need for java.sql.* classes.

Where to obtain the java.time classes?

Java SE 8, Java SE 9, Java SE 10, Java SE 11, and later - Part of the standard Java API with a bundled implementation.
Java 9 adds some minor features and fixes.
Java SE 6 and Java SE 7
Most of the java.time functionality is back-ported to Java 6 & 7 in ThreeTen-Backport.
Android
Later versions of Android bundle implementations of the java.time classes.
For earlier Android (<26), the ThreeTenABP project adapts ThreeTen-Backport (mentioned above). See How to use ThreeTenABP….

The ThreeTen-Extra project extends java.time with additional classes. This project is a proving ground for possible future additions to java.time. You may find some useful classes here such as Interval, YearWeek, YearQuarter, and more.

小开

            String givenStringDate ="07/16/2020";
DateTimeFormatter formatter = DateTimeFormatter.ofPattern("MM/dd/yyyy");
java.util.Date convertedUtillDate;
/*
* If your output requirement is in LocalDate format use below snippet
*
*/
LocalDate localDate =LocalDate.parse(givenStringDate, formatter);
LocalDate localDateLastDayOfMonth = localDate.with(TemporalAdjusters.lastDayOfMonth());


/*
* If your output requirement is in Calendar format use below snippet
*
*/
convertedUtillDate = Date.from(localDate.atStartOfDay(ZoneId.systemDefault()).toInstant());
Calendar calendarLastDayOfMonth = Calendar.getInstance();
calendarLastDayOfMonth.setTime(convertedUtillDate);
int lastDate = calendarLastDayOfMonth.getActualMaximum(Calendar.DATE);
calendarLastDayOfMonth.set(Calendar.DATE, lastDate);

Tested in Java 1.8. I hope this will help some one.

小开

I think the most simple and fastest way is

public static int getLastDayOf(int month, int year) {
switch (month) {
case Calendar.APRIL:
case Calendar.JUNE:
case Calendar.SEPTEMBER:
case Calendar.NOVEMBER:
return 30;
case Calendar.FEBRUARY:
if (year % 4 == 0) {
return 29;
}
return 28;
default:
return 31;
}
}

Since these values are constant universally!

小开

Finally I found the solution is Tested and works

public static Date toDate(String date, String DATE_FORMAT) {
Date dt = null;
try {
String[] d = date.split(" ");
String[] f = DATE_FORMAT.split(" ");
if (d.length > 1) {
if(f.length > 1) {
DateFormat df = new SimpleDateFormat(DATE_FORMAT);
df.setLenient(false);
dt = df.parse(date);
}
else
{
DateFormat df = new SimpleDateFormat(f[0]);
df.setLenient(false);
dt = df.parse(date);
}
} else {
DateFormat df = new SimpleDateFormat(f[0]);
df.setLenient(false);
dt = df.parse(date);
}
return dt;
} catch (ParseException e) {


return null;
}
}


private SimpleDateFormat dateFormatter;
dateFormatter = new SimpleDateFormat("MM/dd/yyyy", Locale.US);
String StartDate = "05/01/2021";
Calendar endDate = new GregorianCalendar();
Date convertedDate = toDate(StartDate, "MM/dd/yyyy");
endDate.setTime(convertedDate);
endDate.set(Calendar.DAY_OF_MONTH, 1);
endDate.add(Calendar.MONTH, 1);
endDate.add(Calendar.DATE, -1);
String EndDate = dateFormatter.format(endDate.getTime());

OutOut: 05/31/2021

在给定的字符串日期中获取月的最后一天

Java 8 and above.

Java 7 and below.

tl;dr

YearMonth

About java.time

`YearMonth`